1. Field of the Invention
The present invention generally relates to the field of producing biocokes using biomass as a raw material, and particularly to a biocoke producing apparatus and process therefor, which enables industrial mass production of biocokes which can be used particularly as substitute fuel for coal cokes.
2. Description of the Related Art
In recent years, in view of global worming, reduction of CO2 emission is promoted. Especially, at combustion facilities like power boiler, fossil fuels such as coal and heavy oil are often used as fuel. However, these fossil fuels are a cause of global warming from a perspective of CO2 emission, and thus the use thereof is becoming more regulated in the view of protecting the global environment. Also from a perspective of fossil fuel drain, there is a need for developing a substitute energy source and putting the source into practical use.
The effort to promote utilization of fuel using biomass instead of coal cokes is being made. In this invention, biomass is an organic matter attributed to photosynthesis such as ligneous matters, grass plants, crops, and kitchen waste. By processing these types of biomass for fuel, it becomes possible to utilize biomass as an energy source or an industrial raw material.
The biomass can be transformed into fuel by drying the biomass to fuel or by pressurizing biomass to a fuel pellet, or by carbonization or destructive distillation. However, in the drying method, air ratio in the dried biomass remains large and apparent specific gravity is small, thus making it difficult to transport or store the fuel. This form of fuel is not very efficient for long distance transportation or storage.
The method to convert biomass into a fuel pellet is disclosed in Japanese Publication S61-27435. This method comprises adjusting moisture content of comminuted fibrous particles to about 16% to about 28% by weight, and compressing the material in a die to dry into the fuel pellet.
The method of destructive distillation is disclosed in JP2003-206490A. According to this method, in oxygen-depleted environment biomass is heated at 200 to 500° C., preferably 250 to 400° C., thus to produce a precursor of charred compact fuel of biomass.
However, according to the method disclosed in Japanese Publication S61-27435, biomass is processed to fuel by pressure-molding, processed fuel pallet contains too much moisture and heat value is low, which is insufficient as fuel.
Moreover, according to a destructive distillation method disclosed in JP2003-206490A and other references, processed biomass has more value than unprocessed biomass but in comparison to coal cokes, still apparent specific gravity is still small and has lower calorific value. It also has lower hardness compared to coal cokes, which is insufficient to substitute coal cokes.